Digital Orthophoto Quadrangles

ABOUT DOQs
An aerial photograph and an orthophoto or orthoimage may look alike but there are several important differences that allow an orthophoto to be used like a map. A conventional perspective aerial photograph contains image distortions caused by the tilting of the camera and terrain relief (topography). It does not have a uniform scale. You cannot measure distances on an aerial photograph like you can on a map. An aerial photo is not a map. The effects of tilt and relief are removed from the aerial photograph by a mathematical process called rectification. An orthophoto is a uniform-scale image. Since an orthophoto has a uniform scale, it is possible to measure directly on it like other maps. An orthophoto may serve as a base map onto which other map information may be overlaid. The preceding description is from the USGS DOQ page.

HOW TO ACCESS DOQs ON THE WEB

http://keck.library.unr.edu

Once the site opens click on the link for Digital Orthophoto Quadrangles (DOQs) under the heading Maps and Geo-Images. Then type in either the DOQ name or County you would like to search (Nevada Counties Only) and submit your request. You will then be forwarded to a site that has all of the available DOQs for the county you requested listed alphabetically by USGS quadrangle name. For each USGS Topographic Quadrangle there are four DOQs so be sure to access all four. Under the name, right click and a little gray box will appear and give you the option to save the target as. Selecte where you would like the file to go and then hit enter. It will begin to download the file to the location you selected. Once complete, there are two ways to open up the data.

DATA ON CD
The information is also available on CDs at Lied Library. The CDs may be checked out and then viewed using either GIS or image viewing software.

ARCVIEW GIS (AVAILABLE IN THE SOGG BUILDING CADD LAB)

This software allows you to open up a number of files and will automatically match the different files together. Select the Arcview GIS 3.2 program.

• A box will appear asking you to create a new project
  
• The selection will default to "with a new view"
  
• Click ok
  
• A box will appear asking if you wish to add data
  
• Click yes
  
• A box will now appear titled "add a theme"
  
• In the bottom left corner change the box labeled "Data Source"
  from "Feature Data Source" to "Image Data Source" by selecting the arrow adjacent to the box
  
• Then select the directory of the DOQs previously downloaded
  
• Select files to open
  
• A box will then appear with the file names on the left side of the screen
  
• Select the box to the left of each file name and a black check mark will appear along
  with the image in the center of the screen

PHOTOSHOP OR OTHER IMAGE VIEWING SOFTWARE

These programs can open up the tiff images but will not automatically line the images up. Once starting the program select file and under the pull down menu select open. A box will appear allowing you to select the destination of the file you wish to open. Locate the file and then click okay. The file will then open.

FREE ARC EXPLORER DOWNLOAD FROM ESRI

ArcExplorer is a lightweight GIS data viewer developed by ESRI. This freely available software offers an easy way to perform basic GIS functions. ArcExplorer is used for a variety of display, query, and data retrieval applications, and supports a wide variety of standard data sources. It can be used on its own with local data sets or as a client to Internet data and map servers. The preceding description is from the ESRI Homepage.
This program is available for download at: http://www.esri.com/software/arcexplorer/

List of DOQs for Las Vegas Valley on the UNR Website

Exact dates are not available at this time. Through visual identification of current landmarks it is estimated that the Las Vegas photos date around 1995.

DOQname	HDR Metadata	Quarter	OhioLocation	OrderSetNo	ItemNo	State	County
blue diamond	blue diamond	NWS	36115A41.tif	7	54	NV	Clark
blue diamond	blue diamond	SES	36115A43.tif	7	55	NV	Clark
blue diamond	blue diamond	NES	36115A42.tif	7	53	NV	Clark
blue diamond	blue diamond	SWS	36115A44.tif	7	56	NV	Clark
blue diamond ne	blue diamond ne	SWS	36115B34.tif	7	60	NV	Clark
blue diamond ne	blue diamond ne	NES	36115B32.tif	7	57	NV	Clark
blue diamond ne	blue diamond ne	NWS	36115B31.tif	7	58	NV	Clark
blue diamond ne	blue diamond ne	SES	36115B33.tif	7	59	NV	Clark
henderson	henderson	NWS	36114A81.tif	7	346	NV	Clark
henderson	henderson	SES	36114A83.tif	7	347	NV	Clark
henderson	henderson	SWS	36114A84.tif	7	348	NV	Clark
henderson	henderson	NES	36114A82.tif	7	345	NV	Clark
las vegas ne	las vegas ne	SES	36115B13.tif	7	427	NV	Clark
las vegas ne	las vegas ne	SWS	36115B14.tif	7	428	NV	Clark
las vegas ne	las vegas ne	NWS	36115B11.tif	7	426	NV	Clark
las vegas ne	las vegas ne	NES	36115B12.tif	7	425	NV	Clark
las vegas nw	las vegas nw	NWS	36115B21.tif	7	430	NV	Clark
las vegas nw	las vegas nw	SES	36115B23.tif	7	431	NV	Clark
las vegas nw	las vegas nw	SWS	36115B24.tif	7	432	NV	Clark
las vegas nw	las vegas nw	NES	36115B22.tif	7	429	NV	Clark
las vegas se	las vegas se	NWS	36115A11.tif	7	434	NV	Clark
las vegas se	las vegas se	SES	36115A13.tif	7	435	NV	Clark
las vegas se	las vegas se	NES	36115A12.tif	7	433	NV	Clark
las vegas se	las vegas se	SWS	36115A14.tif	7	436	NV	Clark
las vegas sw	las vegas sw	NES	36115A22.tif	7	437	NV	Clark
las vegas sw	las vegas sw	NWS	36115A21.tif	7	438	NV	Clark
las vegas sw	las vegas sw	SES	36115A23.tif	7	439	NV	Clark
las vegas sw	las vegas sw	SWS	36115A24.tif	7	440	NV	Clark

---